The present invention relates to a liquid supply system which can be used in a process for manufacturing semiconductors and a method for cleaning the liquid supply system. The present invention is also concerned with a vaporizer used in the liquid supply system.
In recent years, with respect to a process for manufacturing semiconductors, DLI (Direct Liquid Injection) for vaporizing a solution of a solid dissolved in a solvent and supplying the resultant vapor to a system has attracted attention. As a system conducting DLI for supply of a liquid, there can be mentioned the systems disclosed in an article written by the present inventor titled xe2x80x9cDirect Liquid Injection Systemxe2x80x9d in xe2x80x9cKeisoku Gijyutsu (Measurement Technology)xe2x80x9d Vol. 25, No. 12 (January, 1997) published by JAPAN INDUSTRIAL PUBLISHING CO., LTD., Unexamined Japanese Patent Application Public Disclosure (Kokai) No. 5-253402 and U.S. Pat. Nos. 5,361,800 and 5,371,828.
However, due to the supply of liquid by DLI, the above-mentioned systems have problems such as mentioned below. That is, after a certain period of time during use, a solid remains in the system or the state of a solution of the solid dissolved in a solvent changes, thereby adversely affecting the process. Further, with respect to a liquid containing no solid dissolved therein, there is a possibility that a solid component will be produced by thermal decomposition and remain in the system.
In order to solve the above-mentioned problems accompanying the conventional liquid supply systems, the present invention has been made. It is an object of the present invention to provide a liquid supply system by use of which an appropriate time for maintenance can be estimated and the state of a supply liquid can be detected. It is another object of the present invention to provide a liquid supply system which enables appropriate maintenance and a method for cleaning the liquid supply system. It is a further object of the present invention to provide a vaporizer used in the liquid supply system.
According to the present invention, there is provided a liquid supply system comprising:
a first pump for delivering a liquid under high pressure;
a vaporizer for vaporizing the liquid delivered from the first pump to thereby obtain vapor, the vapor being adapted to be introduced into a reaction chamber; and
a passage extending from the first pump to the vaporizer,
wherein a pressure gage is provided in the passage and a monitor device is provided so as to indicate a pressure, based on an output of the pressure gage.
By this arrangement, the pressure in the passage from the first pump to the vaporizer is monitored so as to estimate the amount of decomposition products accumulated in the vaporizer. Therefore, it is possible to estimate the time for cleaning or the time for maintenance.
The present invention also provides a liquid supply system comprising:
a first pump for delivering a liquid under high pressure;
a vaporizer for vaporizing the liquid delivered from the first pump to thereby obtain vapor, the vapor being adapted to be introduced into a reaction chamber; and
a passage extending from the first pump to the vaporizer,
wherein a liquid flowmeter is provided in the passage and a monitor device is provided so as to indicate a flow rate, based on an output of the liquid flowmeter.
By this arrangement, the flow rate of the fluid in the passage from the first pump to the vaporizer is monitored, to thereby enable detection of clogging of the vaporizer or a defect in the pump.
The present invention further provides a liquid supply system comprising:
a first pump for delivering a liquid under high pressure; and
a vaporizer for vaporizing the liquid delivered from the first pump to thereby obtain vapor, the vapor being adapted to be introduced into a reaction chamber,
wherein the liquid supply system further comprises:
a solvent supply system for supplying a solvent for cleaning or a cleaning liquid, the solvent supply system including a second pump for delivering the solvent or the cleaning liquid under high pressure;
a gas supply system for introducing a gas into the first pump and the vaporizer, the gas supply system including a flow rate controller;
a passage for introducing the solvent or the cleaning liquid from the solvent supply system into the first pump and the vaporizer so that the first pump and the vaporizer fill with the solvent or the cleaning liquid; and
a passage for introducing the gas from the gas supply system into the first pump and the vaporizer.
By this arrangement, the system can be cleaned by filling the first pump and the vaporizer with the solvent or the cleaning liquid and introducing the gas into the first pump and the vaporizer through the flow rate controller.
The present invention further provides a method for cleaning a liquid supply system, the liquid supply system comprising a first pump for delivering a liquid under high pressure and a vaporizer for vaporizing the liquid delivered from the first pump to thereby obtain vapor, the vapor being adapted to be introduced into a reaction chamber, the method comprising the steps of:
introducing a solvent or a cleaning liquid into the first pump and the vaporizer so that the first pump and the vaporizer fill with the solvent or the cleaning liquid; and
introducing a gas into the first pump and the vaporizer through a flow rate controller.
By this arrangement, cleaning can be conducted by introducing bubbles into the solvent or the cleaning liquid.
The present invention further provides a vaporizer comprising:
a plurality of disks each including an aperture at an central portion thereof;
a pipe having a hollow structure and having apertures for permitting radial outflow of a liquid, the pipe extending through the aperture of each disk so as to form a stack of disks; and
a resilient member for applying a biasing force so as to bias the plurality of disks,
the liquid in the pipe being adapted to be delivered from the apertures to spaces between the disks and vaporized in the spaces between the disks,
wherein the vaporizer further comprises structure for removing the bias of the resilient member relative to the plurality of disks by applying a force against the biasing force by virtue of fluid control.
By this arrangement, the space between the disks can be increased, so that cleaning can be effectively conducted.
The foregoing and other objects, features and advantages of the present invention will be apparent from the following detailed description and appended claims taken in connection with the accompanying drawings.